pigallery2-metadata-editor

A web-based metadata editor for PiGallery2 that allows reading and writing XMP metadata (such as Favorite, Rating, and Tags) directly from the browser – using ExifTool in the background. All this is accomplished without modifying the PiGallery2 codebase, ensuring long-term compatibility with upstream updates.

Why?

Although PiGallery2 is designed as a read-only photo gallery (a wise decision for safety), I often find myself wanting to make quick adjustments to photo and video metadata – especially when viewing pictures on the web.

For example, I use the F-Stop Gallery app on Android to organize and tag my photos and videos directly on the phone. F-Stop uses a custom XMP tag (XMP-fstop:Favorite) to mark favorites. While this works great on mobile, I wanted a way to adjust this Favorite tag (as well as Ratings and Tags) directly while browsing photos and videos in PiGallery2 – without having to go back to the phone.

Key Benefits:

• Tag or rate photos and videos directly in your browser while viewing them in PiGallery2.
• Immediate visual updates in PiGallery2 after saving metadata – no restart or rescan necessary.
• Modified files synced back to mobile (e.g. F-Stop) show updated tags instantly.
• Safe: all changes are performed via exiftool, optionally with a backup created.
• This setup leaves the PiGallery2 source completely untouched, so you benefit from future updates without merge conflicts.

Architecture

This project uses a single Docker container that exposes:

• Port 9088 for PiGallery2
• Port ${METADATA_API_PORT} (default: 9089) for the metadata API

The metadata editor consists of:

• A small Flask API (app.py)
• A static web UI (ui/index.html, ui/script.js)
• A custom ExifTool_config file (only needed for the Favorite tag used by F-Stop)
• A Dockerfile to build the extended PiGallery2 image
• A docker-compose.yml file to bring everything up together

Setup

You can build and start everything with:

cd src
docker-compose up -d --build

Configuration Notes

You must provide valid volume mappings in docker-compose.yml for the following paths to ensure PiGallery2 works correctly. Make sure to map your image folders in docker-compose.yml to /app/data/images/..., as this is where both PiGallery2 and the metadata editing API expect them to reside.

volumes:
  - "<YOUR_PIGALLERY2_DB_PATH>:/app/data/db"         # Path to your PiGallery2 SQLite database
  - "<YOUR_PIGALLERY2_CONFIG_PATH>:/app/data/config" # Path to your PiGallery2 config directory
  - "<YOUR_PIGALLERY2_TMP_PATH>:/app/data/tmp"       # Path used for temp file storage
  - "<YOUR_PIGALLERY2_IMAGES_PATH>:/app/data/images" # Path to your photo/video folders

Replace the <YOUR_PIGALLERY2_...> placeholders with paths on your host system that point to your actual PiGallery2 directories and media.

Example ports section:

ports:
  - "9088:80"     # PiGallery2 frontend
  - "9089:9089"   # Metadata API

Your start.sh should ensure that the metadata API is listening on the same internal port as defined here:

#!/bin/bash

METADATA_API_PORT=9089

...

UI

Access the web UI via:

http://<your-host>:<METADATA_API_PORT>/meta

From there, you can:

• Paste the PiGallery2 image URL
• Read or update tags (Favorite, Rating, Tags)
• Optionally create a backup of the file before modifying

Bookmarklet

If you are too lazy to copy & paste the PiGallery2 image URL, just add a bookmark to your browser with the following content. Replace <METADATA_API_PORT> by your metadata-API port. Click this bookmark while viewing a specific photo or video in PiGallery2 to open the metadata editor prefilled already with the right image URL.

javascript:(function(){
  const p = new URL(window.location.href);
  if (p.pathname.includes('/gallery') || p.pathname.includes('/search')) {
    const base = p.origin.replace(/:\d+$/, ':<METADATA_API_PORT>');
    const target = base + '/meta/index.html?img=' + encodeURIComponent(p.href);
    window.open(target, '_blank');
  } else {
    alert('Not a PiGallery2 image, search or album page');
  }
})();

Screenshot of loaded metadata

Screenshot of saved metadata

ExifTool Config

The file ExifTool_config is required only to support the XMP-fstop:Favorite tag used by the F-Stop Android app. You may extend this file to define additional custom tags.

License

MIT